Abstract: The present invention provides a high-resolution color picture tube device with a decreased beam spot diameter. The color picture tube device has an electron gun including cathodes, a control electrode, an accelerating electrode, a G3 electrode, a first focusing electrode, a second focusing electrode, and a final accelerating electrode that are arranged in this order. A voltage applied to the G3 electrode is obtained by dividing with a resistor a voltage applied to the final accelerating electrode, and when an electron beam is a non-deflection state, a relationship represented as Va>Vg3>Vfoc2 is satisfied where Va, Vg3, and Vfoc2 denote voltages respectively applied to the final accelerating electrode, the G3 electrode and the second focusing electrode. Thereby, the G3 electrode is applied with a high voltage independently for forming a prefocus lens.

Abstract: The present invention relates generally to an electron gun for a color cathode ray tube, and more particularly to an electron gun for achieving an excellent focus characteristic on the whole screen by forming a dynamic quadruple lens in the electron gun used for a transpose scan type cathode ray tube.

Abstract: An electron gun as for a cathode ray tube includes a plurality of electrodes biased at different potentials to electrostatically shape and focus the one or more electron beams produced thereby. A dynamic focus grid is driven by a substantial ac voltage signal at the horizontal line rate, which signal is undesirably coupled through parasitic capacitance to an intermediate grid located between the dynamic focus grid and the gun anode. A resistive biasing network includes a high value resistance to divide the anode potential to develop bias potential for the intermediate grid and a capacitance to ac couple the intermediate grid to ground potential. The resistance is formed in a single layer ceramic circuit and the capacitance is formed on the single layer ceramic circuit or on the tube neck. The ceramic circuit may be located in the tube neck on or with the electron gun.

Abstract: An autotransformer steps up the output of a high voltage amplifier for applying a drive signal to the focus electrode of a CRT. A parabolic signal is obtained or generated at a deflection frequency such as the horizontal scanning frequency and is applied as an input to the amplifier. The amplifier output is coupled to a center tap of the autotransformer. One winding is serially coupled to the focus electrode and the other winding is AC coupled by a capacitor to ground, in parallel with the amplifier output. The transformer steps up the amplifier output voltage and can reduce the voltage rating required of transistors in the amplifier.

Abstract: Apparatus and method are provided for using a multi-element field emission cathode in a color cathode ray tube. The field emission cathode may have from four to ten field emission arrays linearly arranged. The arrays are preferably formed from carbon-based material. An electron gun assembly focuses electron beams from each array on to a phosphor stripe or dot on the screen of the cathode ray tube. Deflection apparatus moves the beam from each field emission array according to clock signals. Clock signals also turn on or turn off voltage to contacts controlling electron current from the array. Values of voltage applied, determined by a video signal, determine the intensity of electron current from each array, which controls the intensity of the light emitted by each color stripe or dot of phosphor on the phosphor screen.

Abstract: A distortion correcting circuit for correcting vertically asymmetric distortion while achieving reduction in circuit scale and a display apparatus equipped with the circuit are provided.

Abstract: In a circuit and method of controlling the horizontal and vertical screen sizes of a cathode ray tube (CRT) monitor, the circuit includes a horizontal screen size compensation circuit, an east-west correction signal controller, a vertical screen size compensation circuit, and a vertical screen size correction signal controller. The horizontal screen size compensation circuit compares the voltage value of a horizontal screen size correction signal with the voltage value of a horizontal reference voltage to obtain first and second horizontal current signals. In response to a horizontal control signal, the horizontal screen size compensation circuit outputs a horizontal correction current signal obtained by subtracting a horizontal variable current signal from the first horizontal current signal.

Abstract: A dynamic focusing circuit includes a transformer with a primary winding for receiving a line-frequency deflection current and a secondary winding for supplying a transformed deflection current. An integrator, coupled to the secondary winding, generates a line-frequency focusing voltage from the transformed deflection current. A waveform generator coupled to the secondary winding generates an additional line-frequency focusing voltage and superimposes the additional line-frequency focusing voltage on the line-frequency focusing voltage.

Abstract: A color cathode ray tube has an electron gun including three in-line cathodes, first and second grid electrodes arranged in the order named, and plural electrodes for focusing three electron beams from the cathodes onto the phosphor screen. The following inequalities are satisfied: E≦1.4A−0.2B−2.7C−2D, and A≦0.35 mm, where A (mm) is a diameter of an electron-beam transmissive aperture in the first grid electrode, B (mm) is a diameter of an electron-beam transmissive aperture in the second grid electrode, C (mm) is a thickness of a portion of the first grid electrode immediately surrounding the electron-beam transmissive aperture in the first grid electrode, D (mm) is a spacing between the cathodes and the electron-beam transmissive aperture in the first grid electrode, and E (mm) is a spacing between the first grid electrode and the second grid electrode.

Abstract: A color cathode ray tube having an electron gun including an electron beam generating portion arrayed in a horizontal direction for generating three electron beams, and a main lens for focusing the three electron beams from the electron beam generating portion upon a fluorescent face. A final stage of the main lens is formed between a focusing electrode and an accelerating electrode. The focusing electrode is divided into at least two focusing electrode parts. A quadrupole electron lens is formed for each of the electron beams between a first focusing electrode part and a second focusing electrode part, and the strength of the quadrupole electron lens for the central electron beam is different from the strength of the quadrupole electron lens for the side electron beams.

Abstract: The present invention relates generally to an electron gun for a color cathode ray tube, and more particularly to an electron gun for achieving an excellent focus characteristic on the whole screen by forming a dynamic quadruple lens in the electron gun used for a transpose scan type cathode ray tube.

Abstract: A main lens of an electron gun assembly comprises a sixth grid, a seventh grid, an eighth grid, and a ninth grid. An asymmetric lens section is created between a fifth grid and the sixth grid on a cathode side of the main lens. The asymmetric lens section has such asymmetry that lens functions of the asymmetric lens section acting on the electron beams are different between the horizontal direction and the vertical direction, and has a lens power varying in synchronism with the deflection of the electron beams. In this asymmetric lens, the asymmetry for a center beam differs from that for side beams.

Abstract: Disclosed is a deflection yoke which provides a structure for uniformly supporting a PCB on a rear cover of the deflection yoke in order to prevent any damage due to the assembling force when the PCB is assembled onto the rear cover.

Abstract: A cathode ray tube is provided having an electron gun equipped with a main lens having a function of controlling a shape of an electron beam spot which is deflected to the peripheral portion of a display screen, to improve a resolution at the peripheral portion of the screen of the cathode ray tube for use in a direct view color television receiver or a color display terminal. To reduce the dynamic correction voltage of the electron gun, an electrostatic quadrupole lens with a simple structure is used, thereby reducing deterioration due to the deflection aberration of the electron beam spot at the peripheral portion of the screen.

Abstract: A color cathode ray tube (CRT) has an electron-optical system (1) for generating three electron beams (EBR, EBG, EBB), deflection means (2) and a screen (3). In operation, the deflection means (2) deflect the electron beams (EBR, EBG, EBB), so as to change a landing position of the beams on the screen (3). However, by deflecting the beams, the beams are defocused and the spot on the screen (3) changes. In a color cathode ray tube with a relatively large screen, the electron beam defocusing can be observed to be different in strength for each beam (EBR, EBG, EBB). The invention provides a solution to this problem by providing a modified DAF section (40) in the electron-optical system (1). The DAF section (40) comprises at least two electron lenses (L1, L2) having different strengths for each electron beam (EBR, EBG, EBB).

Abstract: A circuit and a method for controlling a delay of a dynamic focus signal are provided. The delay control circuit includes a pulse center detecting circuit, a first delay control signal generating circuit, and a selection circuit. The pulse center detecting circuit generates a center detecting signal that detects a pulse center of a first pulse signal. The first delay control signal generating circuit generates a first delay control signal having a first logic level or a second logic level depending on the result of a comparison of a first comparative signal level generated in a form of a first degree function in response to the first pulse signal with a predetermined second comparative signal level. The selection circuit selects one of the center detecting signal and the first delay control signal in response to a predetermined selection signal and generates the selected signal as a second delay control signal that controls an amount of delay time of the dynamic focus signal.

Abstract: A main lens section of an electron gun assembly includes a focus electrode supplied with a focus voltage of a first level, a dynamic focus electrode supplied with a dynamic focus voltage obtained by superimposing an AC component, which varies in synchronism with deflection magnetic fields, upon a reference voltage close to the first level, and an anode supplied with an anode voltage with a second level higher than the first level. The electron gun assembly further includes at least two auxiliary electrodes disposed between the focus electrode and the dynamic focus electrode, and these at least two auxiliary electrodes are connected via a resistor disposed near the electron gun assembly.

Abstract: A cathode ray tube has a three-gun type electron gun. The electron gun includes a cathode, a G1 electrode, a G2 electrode aligned in line in this order, the G1 electrode and the G2 electrode having beam-passing holes formed therein. A supporting member supports the cathode in position. A GM electrode is added between the G1 and G2 electrodes and has a beam-passing hole smaller than the holes formed in the G1 electrode and the G2 electrode. The supporting member and the G1 electrode are formed with measurement holes. The G2 electrode may also be formed with a measurement hole therein. A measurement element is inserted through the measurement holes to measure a distance between the G1 electrode and the G2 electrode, and a distance between the GM electrode and the G2 electrode.

Abstract: An electron gun assembly for a CRT includes three cathode electrodes, a control electrode, an electron-stream extractor electrode, a focusing electrode, and an anode electrode. The electron-stream extractor electrode includes first, second, and third holes, each of which allows one of the three streams of the electrons to pass through. The focusing electrode includes a flat portion having fourth, fifth, and sixth holes, each of which allows one of the three streams of the electrons to pass through. The first, second, and third holes are arranged in the in-line direction. Each of the fourth and sixth holes includes a substantially rectangular opening and a substantially semicircular opening connected to each other. One side of the substantially rectangular opening is connected to a straight line segment of the substantially semicircular opening, and the substantially rectangular opening is disposed outside while the substantially semicircular opening is disposed inside.

Abstract: In a CRT display apparatus, a horizontal distortion correction apparatus is provided for correcting horizontal distortion of an image by applying a residual phase to control the phase of a horizontal deflection current. The horizontal distortion correction apparatus corrects horizontal distortion of an image caused by an assembly error of the CRT display apparatus for displaying an image by scanning a video signal, based on a horizontal synchronizing signal included in the video signal. The horizontal distortion correction apparatus includes a PLL supplying the horizontal deflection current to a video signal controller for displaying an image on the CRT. A distortion-correcting waveform generator is operated by the user, applying a wave signal having a desired waveform to the PLL to provide a residual phase for the horizontal deflection current to control the phase thereof. As a result, the image without horizontal distortion is displayed on the CRT display apparatus.

Abstract: A device for correcting residual mis-convergence errors in a color cathode ray tube, the tube including a narrow-necked section, located at the rear thereof, in which electron guns mounted therein generate forwardly-directed red, blue and green electronic beams, an outwardly-opening center skirt section, extending forward from the narrow-necked section, and terminating in a wide perimeter surrounding a relatively flat, pixel-coated, viewing screen section that is arranged generally orthogonal to the axis of the narrow-necked section and upon which the electronic beams are directed to strike the pixels to produce color and images for viewing from the front of the tube, and further having at least one pair of electromagnetic coils mounted outside the tube, for initial focusing of the electron beams during their travel from the guns to the screen, the device including a separator made of a plastic, including a high density of magnetizable particles therein, the separator arranged for placement about the outside

Abstract: An autotransformer steps up the output of a high voltage amplifier for applying a drive signal to the focus electrode of a CRT. A parabolic signal is obtained or generated at a deflection frequency such as the horizontal scanning frequency and is applied as an input to the amplifier. The amplifier output is coupled to a center tap of the autotransformer. One winding is serially coupled to the focus electrode and the other winding is AC coupled by a capacitor to ground, in parallel with the amplifier output. The transformer steps up the amplifier output voltage and can reduce the voltage rating required of transistors in the amplifier.

Abstract: A second grid is supplied with a low potential acceleration voltage. A fourth grid and a sixth grid are supplied with a first focus voltage. A third grid and a seventh grid are supplied with a dynamic focus voltage (Vf2+Vd). A prefocus lens having a horizontal and vertical focusing function is formed between the second grid and the third grid. An asymmetrical lens section having a horizontal diverging function and a vertical focusing function is formed between the third grid and the fourth grid. The prefocus lens and the asymmetrical lens section are electrostatically coupled.

Abstract: A cathode ray tube comprising an electron source and an electron beam guidance cavity having an input aperture and an output aperture, wherein at least a part of the wall of the electron beam guidance cavity near the output aperture comprises an insulating material having a secondary emission coefficient &dgr;1 for cooperation with the cathode. Furthermore, the cathode ray tube comprises a first electrode connectable to a first voltage source for applying, in operation, an electric field with a first field strength E1 between the cathode and the output aperture. &dgr;1 and E1 have values which enable electron transport through the electron beam guidance cavity. A second electrode is placed between the cathode and the cavity. The second electrode is connected to a second voltage source for applying, in operation, an electric field with a second field strength E2 between the cathode and the second electrode for controlling the emission of electrons.

Abstract: An electrode assembly includes at least first and second electrodes for forming one or more dynamic quadrupole lenses to emit electron beams and an electron gun using the same. A first parabolic waveform signal having voltages decreasing from the center to the periphery of a screen on which the electron beams land is applied to the first electrode, and a second parabolic waveform signal having voltages increasing from the center to the periphery of the screen is applied to the second electrode, in synchronization with horizontal and vertical deflection signals for horizontally and vertically deflecting electron beams emitted from the electrode assembly.

Abstract: A color cathode-ray tube apparatus comprises an electron gun structure having a plurality of electrodes for constituting a plurality of electron lenses including a main lens for focusing an electron beam on a phosphor screen, and a deflection yoke for producing deflection magnetic fields for deflecting the electron beam emitted from the electron gun structure in a horizontal direction and a vertical direction. An electron beam passage hole formed in at least one of the electrodes constituting the main lens has a waist portion substantially acting on formation of the electron lenses. The waist portion minimizes a horizontal dimension of a region where the electron beam passes.

Abstract: A cathode-ray tube electron gun can alleviate unwanted radiation caused when cathodes and a first electron gun constitute an antenna by increasing the number of conduction leads of a first electrode of a cathode-ray tube electron gun from one to a plurality of conduction leads.

Abstract: An electron gun for a color CRT includes a triode including cathodes for emitting electron beams, a control electrode, and a screen electrode, at least two focusing electrodes on the same axis of the triode portion for forming a quadrupole lens, and a final focusing electrode forming a large diameter lens with the focusing electrodes and through which three electron beams commonly pass. The electron gun includes a correction unit producing a correction force acting on the three electron beams and that is larger for two side electron beams than for a central electron beam of the three electron beams when a dynamic voltage, synchronized with a deflection signal, is applied to at least one of the focusing electrodes for forming the quadrupole lens.

Abstract: The screen electrode in an electron gun for use in a cathode ray tube has multi-stage apertures such that the entrance area of an aperture is larger than the exit area. This has an effect of smaller screen electrode apertures with a result of increased pre-focusing of electron beams passing through the apertures. Thus, increased pre-focusing reduces the beam incident angle to the main lens. A smaller beam incident angle generates less spherical aberration in the main lens.

Abstract: The stray emission in an electron gun comprising a main lens system with one or more intermediate electrodes (42, 43, 44) between the focus electrode (41) and the anode electrode (45) is reduced if at least one of the apertures of the main lens system following the focus electrode has apertures which are smaller than those of the focus electrode. The optimal stray emission situation can be found by designing all the apertures of the main lens system. In order to manufacture an electron gun according to the invention, it is advantageous to have an outside reference system for gun mounting, because it will no longer be possible to center the electrodes on pins through the apertures.

Abstract: A method of compensating for and correcting temperature induced focus and distortional errors within a head-up display unit is described. The head-up display is comprised of a cathode ray tube and a plurality of lenses constructed of a plastic material defining a lens train and a mounting device constructed of a metal material. The compensation for the temperature can be accomplished by measuring the difference in thermal expansion between the plastic material and the metal material and conveying the measured difference to an alignment device for an appropriate adjustment.

Abstract: A focusing circuit (1) for generating a focus control signal for a cathode ray tube (3) has a modulation input (4) for influencing the focus control signal, which focus control signal contains a measure for an envelope of excursions of horizontal scan lines across the cathode ray tube. The focusing circuit (1) comprises a load control circuit (5) for influencing the focus control signal, and having a control input (6) coupled to the modulation input (4) for influencing the focus control signal by load control variation in dependence on a desired focus control signal modulation. The load control circuit (5) may comprise a current source and/or a voltage source and/or controllable impedance that have a control input for coupling to a modulation output of a synchronization processor (7).

Abstract: A cathode ray tube assembly includes a funnel having a neck, an electron gun having an electron emitter within the neck and having at least two focus electrodes for forming an electron lens for focusing and accelerating electron beams emitted from the electron emitter, lead pins extending through the neck and connected to the first and second focus electrodes, and a socket with pin connection terminals connectable to the lead pins; a voltage applying unit for applying an AC voltage to at least one of the focus electrodes through a lead pin connected to the focus electrode; and a voltage drop unit for reducing the AC voltage applied by the voltage applying unit to a second of the focus electrodes so that a reduced voltage is applied to a lead pin connected to the second focus electrode, the voltage drop unit being connected to the lead pins through pin connection terminals of the socket.

Abstract: The invention relates to a dynamic focusing circuit (100) for generating a line-frequency dynamic focusing voltage (Vl1) which can be used to control a DAF section (220) of a cathode ray tube (CRT). The dynamic focusing circuit (100) receives a line deflection current (Id1) and transforms and integrates said current so as to obtain the line-frequency focusing voltage (Vl1). The dynamic focusing circuit also generates a further line-frequency focusing voltage (Vl2) and adds this voltage to the line-frequency focusing voltage (Vl1). By applying the invention, the line-frequency focusing voltage (Vl1) is suitable for dynamically focusing the electron beam (201) in a cathode ray tube (CRT) with a relatively large deflection angle of, for example, 120°. It has both a sufficient amplitude and a suitable shape, for example, a bathtub shape.

Abstract: A dynamic focus electron gun for a color cathode ray tube including a cathode, a control electrode and a screen electrode, which constitute a triode, a first focusing electrode having three vertically elongated electron beam through-holes formed through its emitting surface, a second focusing electrode which constitutes a quadrupole lens together with the first focusing electrode and having three circular electron beam through-holes formed through its entering surface facing the emitting surface of the first focusing electrode, and a final accelerating electrode installed adjacent to the second focusing electrode and constituting a main electronic lens together with the second focusing electrode.

Abstract: A color TV tube apparatus having a horizontal deflection coil for generating a pincushion-shaped horizontal deflection field, which uses a self-convergence method. In such a color TV tube, the horizontal deflection coil is adjusted so that the vertical focus points of the electron beams lie 50 mm or less on the inside and 30 mm or less on the outside of each edge of the effective display screen area along the horizontal axis. The horizontal deflection coil is adjusted with the focusing of an electron beam by a lensing action of an electron gun non-operational.

Abstract: An electron gun for a color cathode ray tube includes a first electrode, a second electrode and a third electrode. A waveform alternating voltage or a static voltage is applied to the first electrode in which three vertical slot type electron beam passing holes are formed. The second electrode is installed at one side of the first electrode in which circular electron beam passing holes are formed. The third electrode is disposed at the other side of the first electrode. A single horizontal slot type electron beam passing hole is formed in the third electrode to which the same dynamic focus voltage as that in the second electrode is applied.

Abstract: An electron gun assembly has at least one additional electrode located along the equipotential plane of a potential distribution formed between a focusing electrode and anode electrode forming a main lens. In a no-deflection state, the additional electrode receives a voltage of a predetermined level corresponding to the potential of the equipotential plane on which the additional electrode is located. In a deflection state, letting Vf be the application voltage of the focusing electrode, Eb be the application voltage of the anode electrode, and Vs be the application voltage of the addition electrode, a value (Vs−Vf)/(Eb−Vf) changes with an increase in electron beam deflection amount, while the additional electrode forms an electron lens having different focusing powers in the horizontal direction and vertical direction.

Abstract: An electric field expansion type main lens portion is constituted by including a focus electrode to which a focus voltage on a first level is applied, an anode electrode to which an anode voltage on a second level higher than the first level is applied, and two auxiliary electrodes to which a voltage on a third level higher than the first level and lower than the second level is applied and which are arranged between the focus electrode and the anode electrode. An electrode length of each of the two auxiliary electrodes along an electron beam traveling direction is constituted so as to differ in accordance with a difference in potential between electrodes arranged at front and rear positions in the electron beam traveling direction of each auxiliary electrode.

Abstract: A color display device with an improved focus performance. Conventional color display tubes with DAF have an electron gun with a second focusing electrode (25) driven with a dynamic voltage which is varied synchronously with the deflection field. The dynamic quadruple lens formed between the first focusing electrode (23) and the second focusing electrode (25) is designed such that the horizontal lens action, which arises when the voltage on the second focusing electrode is increased, should be compensated by the main lens which becomes weaker when the voltage on the second focusing electrode is increased. In practice, this is not possible in the required range of the dynamic voltage on the second focusing electrode, leading to a deterioration of the focus performance of the color display device.

Abstract: An electron gun structure includes a first non-axial-symmetrical lens portion which is arranged in the vicinity of an electron beam formation portion, and a second non-axial-symmetrical lens portion formed to a main lens portion, the first non-axial symmetrical lens portion has a lens action in the vertical direction that a focusing action relative to the electron beams becomes stronger as a quantity of deflection of the electron beams increases, and a lens action in the horizontal direction which substantially rarely acts on the electron beams, and a comprehensive lens system of the second non-axial-symmetrical lens portion and the main lens portion has a lens action in the vertical direction that a divergence action relative to the electron beams becomes stronger as a quantity of deflection of the electron beams increases, and a lens action in the horizontal direction which substantially rarely acts on the electron beams.

Abstract: A display apparatus includes a CRT, the CRT including an electron gun having a cathode, a G1 electrode, a G2 electrode, and a G3 electrode disposed in that order to draw electrons from the cathode. The electron gun further has a modulating Gm electrode disposed between the G2 and G3 electrodes. The display apparatus is provided with a controller for controlling a value of a voltage applied to the Gm electrode to adjust brightness of a picture on a screen of the CRT.

Abstract: A color cathode ray tube apparatus of this invention includes an electron gun. In the electron gun, an intermediate electrode is arranged at the mechanical center between a focus electrode and anode electrode that form a rotationally symmetric bi-potential lens. A disk-like intermediate electrode is arranged at the mechanical center between the focus electrode and intermediate electrode. The disk-like intermediate electrode has an electron beam hole with a diameter larger in the vertical direction than in the horizontal direction. The intermediate electrode has a circular electron beam hole. Voltages are applied to the disk-like intermediate electrode and intermediate electrode such that they form an electron lens similar to that formed when the disk-like intermediate electrode does not exist. Therefore, an electron beam spot is focused in an optimal manner on the entire surface of a phosphor screen, and elliptic distortion is decreased. A good image is displayed on the entire surface of the phosphor screen.

Abstract: A laser CRT includes a cathode, a modulator having an orifice for forming an electron beam from the electrons emitted by the cathode, and a beam directing unit directing the electron beam formed by the orifice of the modulator to the laser screen of the laser CRT. To reduce the diameter of the electron beam and to thereby improve the resolution of the laser CRT, the laser CRT includes at least one other modulator having an orifice for forming another electron beam from the electrons emitted by the cathode, the beam directing unit being adapted for directing the other electron beam formed by the at least one other modulator to the laser screen.

Abstract: A sixth grid, which is part of a main electron lens section, is made up of a first anode, an auxiliary electrode and a second anode. A fifth grid is applied with an intermediate voltage. The first and second anodes are applied with an anode voltage. An intermediate electrode and the auxiliary electrode are applied with a voltage whose level is between the levels of the intermediate voltage and anode voltage.

Abstract: A color cathode ray tube includes third, fourth and fifth electrodes and an anode in its electron beam focusing section.

Abstract: The cathode ray tube apparatus comprises a main lens constructed by focus, intermediate, and final acceleration electrodes. The main lens includes a focusing area positioned in a side of the focus electrode, and a diverging area positioned in a side of the final acceleration electrode. A focusing force curve expressing the focusing force along the tube-axis direction in the focusing area has two convex parts respectively being at first and second levels, and a concave part provided between the convex parts and being at a third level sufficiently lower than the first and second levels. The third level is set to a lowermost level at which a focusing or diverging force is not substantially effected on the electron beam. An intermediate electrode having a non-circular shaped hole is positioned near an area of the lowermost level.

Abstract: A method for operating a cathode-ray tube electron gun, suitable for multimode operation, for example, in order to display television images and multimedia images of the SVGA, XGA type, in which the zone for forming the electron beam generated by the cathode has at least two control electrodes. The two control electrodes are connected to voltage sources in such a way that the potential difference between the two control electrodes increases when the beam current decreases.

Abstract: A cathode ray tube including a bulb having a screen on which a fluorescent film is formed, and a funnel portion having a neck portion on the side opposite to the screen, an electron gun mounted in the neck portion of the bulb, a deflection yoke mounted on the bulb, for deflecting an electron beam emitted from an electron gun, a velocity modulator installed around the neck portion, and an eddy current generation preventing means installed on an electrode of the electrode gun, which corresponds to the velocity modulator, for preventing generation of an eddy current by the velocity modulator. Here, the electron gun has a cathode forming a triode portion, a control electrode, a screen electrode, a plurality of focusing electrodes sequentially aligned from the screen electrode, and a final accelerating electrode which is installed adjacent to a focusing electrode the farthest away from the cathode or protects a predetermined width of the outer circumferential surface of the focusing electrode.

Abstract: An electron gun for a color cathode ray tube includes cathodes, a control electrode, and a screen electrode, forming a triode, first, second, third, and fourth focusing electrodes, sequentially arranged relative to the screen electrode and forming at least one first quadrupole lens, fifth and sixth focusing electrodes, adjacent to the fourth focusing electrode and forming at least one second quadrupole lens, and a final accelerating electrode, adjacent to the sixth focusing electrode and forming a main lens.